Track assembly for an all-terrain vehicle

ABSTRACT

The present invention relates to a track assembly adapted to be retrofitted to an all-terrain vehicle having a driving output. The track assembly comprises an endless track belt extending over at least a pair of longitudinally spaced-apart inner wheels and a driving arrangement adapted to be drivingly connected to the driving output of the all-terrain vehicle for transmitting power to the endless track belt. The driving arrangement comprises at least one driving wheel mounted outside of a loop defined by the endless track belt and in driving engagement therewith. It also relates to a steering mechanism for an all-terrain vehicle having a pair of front track assemblies, each having at least one driving wheel.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35USC§119(e) of U.S. provisionalpatent application 60/577,924, filed on Jun. 9, 2004, the specificationof which is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1) Field of the Invention

The present invention relates to all-terrain vehicles and, moreparticularly to track assemblies for all-terrain vehicles.

2) Description of the Prior Art

Traditionally, two types of all-terrain vehicles are proposed either thewheeled type or the tracked type. Wheeled vehicles are usually moremaneuverable than tracked vehicles but are not as efficient on uneven orsoft terrain such as snow.

Mainly two types of track systems have been proposed. U.S. Pat. No.6,006,847 describes an endless track structure having a substantiallytriangular shape. An endless track belt is mounted over front and rearidler wheels and two spaced apart driving wheels mounted on the existingwheel hub of the vehicle. The idler wheels are located below the drivingwheels and are interconnected with sliding shoes. The track belt of U.S.Pat. No. 6,006,847 has a wide supporting footprint. U.S. patentapplication Ser. No. 10/165,707 describes an endless track structurehaving also a substantially triangular shape wherein an endless trackbelt is mounted over front and rear idler wheels a driving wheel mountedon the existing wheel hub of the vehicle. However, the idler wheels arelocated above the driving wheel and therefore the track belt has apunctualized localized surface with the ground.

The track structure of U.S. Pat. No. 6,006,847 gives better performancewhen the vehicle is in deep snow conditions than the track structure ofU.S. patent application Ser. No. 10/165,707. However, the performance ofU.S. Pat. No. 6,006,847 decreases when the ground surface is harder.Moreover, since it includes sliding shoes, it can only be used in snowconditions. Since the track structure of U.S. patent application Ser.No. 10/165,707 does not have sliding shoes, it can be used on any groundsurfaces.

There is therefore a need for a new track assembly for an all-terrainvehicle that gives as good performance as the track system of U.S. Pat.No. 6,006,847 in snow conditions and can be used on any ground surface.

SUMMARY OF THE INVENTION

An object of the present invention is therefore to provide improvedtrack assemblies for an all-terrain vehicle.

According to one aspect of the present invention, there is provided astraddle-type vehicle including at least one track assembly to supportvehicle onto a ground surface. The at least one track assembly comprisesa longitudinal endless track belt having an outer surface and an innersurface; a frame to mount the longitudinal endless track belt to thevehicle; at least one driving wheel disposed externally to thelongitudinal endless track belt, the at least one driving wheel being indriving engagement with the longitudinal endless track belt; and atleast two inner wheels in contact with the inner surface of thelongitudinal endless track belt.

According to another aspect of the present invention, there is provideda track assembly for an all-terrain vehicle. The track assemblycomprises a longitudinal endless track belt having an outer surface andan inner surface and a mounting structure to mount the longitudinalendless track belt to the vehicle. The mounting structure includes atleast one driving wheel disposed externally to the longitudinal endlesstrack belt, the at least one driving wheel being in driving engagementwith the longitudinal endless track belt, and at least two inner wheelsin contact with the inner surface of the longitudinal endless trackbelt.

According to a further aspect of the present invention, there isprovided a mechanism for facilitating the steering of an all-terrainvehicle having a pair of track assemblies. Each track assembly has atleast one driving wheel. The mechanism comprises at least one first andsecond braking systems operatively connected to respective drivingwheels of the pair of track assemblies; the first and second brakingsystems being independently actuable, whereby upon activating one of thefirst and second braking systems, the driving wheel operativelyassociated with the actuated braking system is slowed down to facilitateturning of the vehicle in the direction of the slowed down drivingwheel.

According to another aspect of the present invention, there is providedan all-terrain vehicle including a steering mechanism and a pair offront track assemblies. Each of the track assemblies comprises at leastone driving wheel and at least one independent braking systemoperatively connected to the at least one driving wheel; the brakingsystems of the track assemblies being selectively independentlyactuable, whereby upon actuating one of the braking system, the drivingwheel operatively associated with the actuated braking system slows downallowing the vehicle to turn in the direction of the slowed down drivingwheel.

According to another aspect of the present invention, there is provideda method to facilitate the steering of an all-terrain vehicle having apair of front track assemblies, each having at least one driving wheel.The method comprises providing at least first and second brakingsystems; operatively connecting the first and second braking systems torespective ones of the track assemblies; and providing independentcontrol of the first and second braking systems.

According to another aspect of the present invention, there is provideda method to facilitate the steering of an all-terrain vehicle having apair of left and right track assemblies. The left and right trackassemblies respectively includes left and right driving wheels and leftand right brakes. The method comprises the step of providing independentcontrol of the left and right brakes, whereby upon independentlyactuating one of the left and right brakes, only the driving wheelassociated to the actuated brake is slowed down creating a speeddifferential between the left and right track assemblies to facilitatesteering of the vehicle in the direction of the slowed down drivingwheel.

According to a still another aspect of the present invention, there isprovided a track assembly adapted to be retrofitted to a straddle typevehicle having a driving output. The track assembly comprises an endlesstrack belt extending over at least a pair of longitudinally spaced-apartinner wheels, and a driving arrangement adapted to be drivinglyconnected to the driving output of the straddle type vehicle fortransmitting power to the endless track belt, wherein the drivingarrangement comprises at least one driving wheel mounted outside of aloop defined by the endless track belt and in driving engagementtherewith.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features and advantages of the present invention will becomeapparent from the following detailed description, taken in combinationwith the appended drawings, in which:

FIG. 1. is a side elevation view of an all-terrain vehicle provided withtrack assemblies according to a preferred embodiment of the presentinvention;

FIG. 2 is a photograph of an inside perspective view of a mountingstructure according to the present invention, with a longitudinalendless track belt mounted thereon and wherein the mounting structure ismounted on an all-terrain vehicle;

FIG. 3 is an outside perspective view of the mounting structureaccording to the present invention, without the track belt;

FIG. 4 is an enlarged outside perspective view of the mounting structureaccording to the present invention, without the track belt;

FIG. 5 is an inside perspective view of the mounting structure accordingto the present invention, without the track belt;

FIG. 6 is a top plan view of the mounting structure according to thepresent invention, without the track belt;

FIG. 7 is a photograph of a front elevation view of the mountingstructure according to the present invention, with the track beltmounted thereon and wherein the mounting structure is mounted on anall-terrain vehicle; and

FIG. 8 is a photograph of a top perspective view of the mountingstructure according to the present invention, with the track beltmounted thereon and wherein the mounting structure is mounted on anall-terrain vehicle.

FIG. 9 is a side elevation view of an all-terrain vehicle provided withtrack assemblies according to a second embodiment of the presentinvention;

FIG. 10 is an inside perspective view of a mounting structure with alongitudinal endless track belt mounted thereon according to the presentinvention;

FIG. 11 a front elevation view of the mounting structure of FIG. 10 withthe longitudinal endless track belt mounted thereon according to thepresent invention; and

FIG. 12 an outside perspective view of the mounting structure of FIG. 10with the longitudinal endless track belt mounted thereon according tothe present invention.

It will be noted that throughout the appended drawings, like featuresare identified by like reference numerals.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

A track assembly adapted to be retrofitted to a wheeled type all-terrainvehicle according to an embodiment of the present invention will now bedescribed in details with reference to the appended drawings.

FIG. 1 shows an all-terrain vehicle 10 comprising a body 12 and fourtrack assemblies 14 (only two are shown) arranged in a plane adjacent toeach side of the vehicle 10. The four track assemblies 14 of theall-terrain vehicle 10 are identical and replace the conventional wheelsof the all-terrain vehicle 10. Only one track assembly 14, visible inFIG. 1, will be described hereinbelow.

Referring to FIGS. 2 and 10, it will be seen that the track assembly 14comprises a longitudinal endless track belt 20 and a mounting structureto mount the endless track belt 20 to the vehicle 10. The mountingstructure includes a main driving wheel 24, a pair of track drivingwheels 26 disposed on opposite sides of the rotation axis of the maindriving wheel 24 (only one is shown in FIG. 2), and a plurality of inneridler wheels 28 disposed by pair inside longitudinal endless track belt20, and supports to interconnect the wheels 24, 26 and 28 as will bedescribed hereinbelow. The idler wheels 28 define two laterallyspaced-apart rows of longitudinally spaced-apart wheels. As it can beseen from FIGS. 2, 7, 8, and 10-12, main driving wheel 24 and trackdriving wheels 26 are external to endless track belt 20.

Referring back to FIGS. 2 and 10, the endless track belt 20 is made ofan elastomeric material and has an outer surface 30 for contact with theground and an inner surface 32. Outer surface 30 is provided withtransversal lugs 34 and is adapted to engage with the driving wheels 26of the vehicle 10. The endless track belt 20 is also provided withequidistant longitudinally spaced-apart openings 36 for engagement withthe track driving wheels 26. Adjacent openings 36 are separated by abridging web 38. Bridging webs 38 are preferably covered with areinforcing member 39 to increase the life expectancy of the endlesstrack belt 20. The endless track belt 20 is wounded around the inneridler wheels 28 while the main driving wheel 24 and the track drivingwheels 26 are located outside the loop defined by endless track belt 20.

Referring now simultaneously to FIGS. 2 to 4, 10, it will be seen thattrack driving wheels 26 are preferably provided in the form of cogwheelswith equidistant teeth 40.

In the embodiment of FIG. 2, track driving wheels 26 are separated intwo members. A first member 42 has teeth 40 a that cooperates with thetransversal lugs 34 provided on the outer surface 30 of the endlesstrack belt 20 while a second member 44 has teeth 40 b that cooperateswith bridging webs 38 between openings 36. Teeth 40 a, 40 b are spacedso that the distance between two consecutive teeth 40 a, 40 b spans thedistance separating consecutive transversal lugs 34 and bridging webs 38respectively, in a meshing engagement, in such a way as to drive theendless track belt 20. As it will be easily understood by one skilled inthe art, the track driving wheel 26 can have only one member (FIGS. 3,4, and 10-12) that cooperates with either transversal lugs 34 of theendless track belt 20 or bridging webs 38, whichever the endless trackbelt 20 includes. In the embodiment of FIG. 10, track driving wheels 26cooperate with bridging webs 38 between openings 36. Teeth 40 are spacedso that the distance between two consecutive teeth 40 spans the distanceseparating consecutive transversal lugs 34 and/or bridging webs 38respectively, in a meshing engagement, in such a way as to drive theendless track belt 20.

The main driving wheel 24 is retrofitted to the existing hub 50 of theall-terrain vehicle 10 (FIG. 2). Referring simultaneously to FIGS. 2-4,and 10, it will be seen that the main driving wheel 24 includes aninside plate 52 mounted to the hub 50 and an outside plate 54 mounted tothe inside plate 52 via a bolt and spacer assembly 56. Inside plate 52has an outer surface 60 and an inner surface 62. A plurality ofuniformly circumferentially distributed engaging members 64 are providedon either the outer surface 60 (FIG. 2) or the inner surface 62 (FIGS.3-5) of inside plate 52. Engaging members 64 cooperate with the teeth 40of track driving wheels 26. Equidistant engaging members 64 are spacedso that the distance between two consecutive engaging members 64 spansthe distance separating consecutive teeth 40, in a meshing engagement,in such a way as to drive track driving wheels 26. As it will be easilyunderstood by one skilled in the art, engaging members 64 can also bethe spacers between the inside and outside plates 52, 54 (FIGS. 10-12)or be mounted on either the inner or outer surface of outside plate 54.According to one embodiment of the present invention, the engagingmembers 64 are provided in the form of rollers to provide a smoothtorque transmission from the main driving wheel 24 to the track drivingwheel 26.

Wheels 24, 26 and 28 are interconnected with an inside mounting plate 70and an outside mounting plate 72, wheels 24 and 26 being disposedexternally to track belt 20. Inside plate 52 of main driving wheel 24 isconnected to outside mounting plate 70 with a spacer 80. Referring toFIG. 6, it will be seen that spacer 80 has three portions 80 a, 80 b,and 80 c, each portion having a different diameter. Inside plate 52 isrotatably mounted on spacer 80. Referring back to FIGS. 2-4, 10 and 12,it will be seen that each track driving wheels 26 is rotatably mountedon a spacer 82 which connects inside and outside mounting plates 70, 72.Similarly, each pair of inner idler wheels 28 is rotatably mounted on aspacer 84 which connects inside and outside mounting plates 70, 72.Spacers 80, 82, and 84 are fastened to inside and outside mountingplates 70, 72 with fasteners 86 inserted in apertures in inside andoutside mounting plates 70, 72 but they could be welded thereon withoutdeparting from the scope of the invention. A reinforcing plate 90 (FIGS.2-5) can interconnect spacer 80 and spacers 82. Reinforcing plate 90reinforces outside plate mounting 72 and stiffens the track assembly 14.

Each of the inner idler wheels 28 has a peripheral portion in contactwith the inner surface 32 of the track belt 20. In a preferredembodiment, track assembly 14 has a plurality of pairs of inner idlerwheels 28. Each pair is rotatably mounted on each spacer 84. Moreover,any number of inner idler wheels 28 can be rotatably mounted on eachspacer 84 without departing from the scope of the invention.

As it will be easily understood by one skilled in the art uponinspection of FIGS. 2, 3, 10, and 12, the shape of the endless trackbelt 20 can be modified by adjusting the vertical position of the frontand rear idler wheels 28 a, 28 b. As it can be seen, both ends of insideand outside mounting plates 70, 72 have several round apertures 91, atvarious height, in which spacer 84 can be fastened. By mounting spacer84 in a higher round aperture 91 positioned at one end, endless trackbelt 20 has a C-shape at that end as seen in FIGS. 2 and 10. On theopposite, by mounting spacer 84 in a lower round aperture 91 at anotherend, endless track belt 20 has a substantially flat shape at that end.An endless track belt 20 having a C-shape is more maneuverable while anendless track belt 20 that is substantially flat gives betterperformance since it has a wider supporting footprint.

It is also possible to adjust the tension of endless track belt 20 witha tension adjusting assembly. As it can be seen from FIGS. 2, 3, 10, and12, one end of inside and outside mounting plates 70, 72 includesseveral slotted apertures 92, one slotted aperture 92 for each roundaperture 91. Slotted aperture 92 receives a fastener 94 used torotatably mount the wheels 28 to the assembly. By sliding the fastener94 in the slotted aperture 92, it is possible to increase or decreasethe tension on the track belt 20. To adjust and maintain the tracktension, a cam element 96, having an outer periphery provided withnotches 98 located at different distances from the attachment point ofthe cam element 96, is mounted to the fastener 94. By selecting whichnotch 98 is in contact with a fixed pin (not shown) of the cam element96, a predetermined tension may be maintained. It is to be noted thatthe cam element 96 can be provided with a handle (not shown) tofacilitate the manipulation by a user. It is also understood that thetension adjusting assembly can be located at the opposite end of theinside and outside mounting plates 70, 72.

Inside mounting plate 70 has a central aperture 100 (FIG. 5) forinserting conventional hub 50 of the all-terrain vehicle 10 therein. Italso has small apertures 102 all around the central aperture 100 forinserting fasteners (not shown) therein for fastening the track assembly14 to the vehicle 10.

It is possible to adjust the height of the track assembly 14 bymodifying the position of driving track wheels 26 relatively to maindriving wheel 24. As it can be seen from FIG. 4, inside and outsidemounting plates 70, 72 are provided with a plurality of round apertures104 in which spacer 82 can be fastened with fasteners 86. A roundaperture 104 on inside mounting plate 70 faces a corresponding roundaperture 104 on outside mounting plate 72. By fastening spacer 82, onwhich driving track wheel 26 is rotatably mounted, in different roundapertures 104, the height of track assembly 14 is modified. Inside andoutside mounting plates 70, 72 are also provided with a central roundaperture 104. If track assembly 14 only has one track driving wheel 26operatively engaged with the main driving wheel 24 and the longitudinaltrack driving belt 20, spacer 82, on which the single driving trackwheel 26 is rotatably mounted, is preferably fastened with fasteners 86in central round aperture 106 (FIG. 2). However, with two driving trackwheels 26, the vehicle rolling is smoother.

The track assembly 14 also allows to replace any of the driving wheels24, 26 with another wheel having a different diameter. Changing thedriving wheels 24, 26 allows to modify the gear ratio of the vehicle 10.

It is also possible to cover the external gearing of the track assembly14, which includes main driving wheel 24 and driving track wheels 26,with a protective cover (not shown). The protective cover prevents theinsertion of undesired objects, such as branches, in the track assembly14 and further acts to reduce the security risk associated withoperating such a track assembly 14, for the vehicle's user or any otherperson in proximity of the track assembly 14.

As stated hereinabove, the track assembly 14 is provided with anexternal gearing, i.e. the main driving wheel 24 and the track drivingwheel are located externally of endless track belt 20. The endless trackbelt 20 has a plurality of equidistant openings 36 separated by bridgingwebs 38, which ensure a positive engagement with the teeth 40 providedon the outer circumference of track driving wheels 26. Moreover, themain driving wheel 24 is provided with a plurality of equidistantengaging members 64, which ensure a positive engagement of the teeth 40.In operation, the main driving wheel 24 is coupled to a drive shaft, viathe hub 50, connected to an engine (FIGS. 2, 7, and 8), in such a waythat the engine drives the main driving wheel 24 in rotation. The maindriving wheel 24 thus drives both track driving wheels 26 in rotation bymeshing engagement of the teeth 40 and the equidistant engaging members64. The track driving wheels 26 drives the endless track belt 20 inrotation by the meshing engagement of the teeth 40 with the equidistantopenings 36 separated by bridging webs 38 of the endless track belt 20.It is further to be understood that the transversal lugs 34 on theexternal circumference surface of the endless track belt 20 respectivelyexert a positive mechanical connection with the underlying groundsurface that contributes to propel the vehicle 10.

In another embodiment, the track assembly 14 includes a steeringmechanism that facilitates the steering of the all-terrain vehicle 10.Referring to FIGS. 3 to 6, it will be seen that the steering mechanismincludes two secondary braking systems. Each braking system isoperatively associated with a track assembly 14 disposed at the front ofthe all-terrain vehicle 10, mainly with the main driving wheel 24 of theassembly 14. Each secondary braking system includes a brake 140. Thebrake 140 is disposed proximate to the main driving wheel 24. In FIGS. 3to 6, the brake 140 is mounted proximate to the outside plate 54 andabuts against the latter when the braking system associated with thebrake 140 is activated. The brake 140 abutting the outside plate 54slows down the rotation movement of the main driving wheel 24 andconsequently the rotation movement of the track belt 20. When theall-terrain vehicle 10 negotiate a turn in a predetermined direction,the braking system associated with the main driving wheel 24 locatedinside the desired turn can be activated to provide better maneuveringof the vehicle. The main driving wheels 24 of the front track assemblies14 have therefore a different rotation speed and the vehicle 10 turns inthe direction of the main driving wheel 24 having the slowest rotationspeed. Moreover, for tracked vehicle, since the rotation pivot is offsetrelatively to the track belt 20, the vehicle steering is even morefacilitated.

The steering mechanism can be activated manually with a handle, a pedal,or the like or automatically while turning the steering of the vehicle.The steering mechanism can be combined with the main braking system ofthe vehicle without departing from the scope of the invention. Eachbraking system can be operatively associated simultaneously with a frontand a rear driving wheels on the same side of the vehicle 10. Brakes 140can be operatively associated with the track driving wheels 26, on theinside plate 52 of the main driving wheel 24 or both inside and outsideplates 52, 54 without departing from the scope of the invention.Preferably, the plate(s) or wheel(s) associated with each brake 140 ismade in steel or any other appropriate material.

Of course, one skilled in the art could design another arrangement ofthe mounting assembly of the endless track belts 20 to the vehicle 10 toobtain this external driving wheel feature without departing from thespirit and nature of the present invention.

Alternatively, the track assembly 14 could only be comprised of a maindriving wheel 24 directly engaged with the longitudinal track drivingbelt 20. In that case, the main driving wheel 24 would be provided withequidistant teeth 40 on its periphery for meshing engagement with eitherthe transversal lugs 34 and/or the equidistant openings 36 separated bybridging webs 38. Furthermore, the motor of the all-terrain vehicle 10preferably turns in the opposite direction.

As people in the art will understand, the all-terrain vehicle of thepresent invention, provided with four endless track assemblies, can beused for a wide range of operations and terrain, while being highlymobile and offering good running performance. The endless trackstructure maintains an adequate configuration over a variety ofsurfaces. Since it does not have sliding shoes, it can be used on anyground surface.

Moreover, the track assembly 14 can be used with all-terrain vehicle 10of any cylinder capacity. As it can be seen in FIGS. 1 and 9, the trackassembly 14 provides support longitudinally under almost the entireall-terrain vehicle 10, including under the lower portion 120 of thevehicle 10. It provides a wide supporting footprint that performsadequately in deep snow conditions. The snow projected on the driverwhile using an all-terrain vehicle 10 having the track assembly 14 isnegligible. Moreover, as it can be seen in FIGS. 1 and 9, the wings ofthe all-terrain vehicle 10 are clear from the track assemblies 14.Therefore, even if the track assembly 14 pivots around hub 50, the riskof interference with the wings is negligible.

Referring back to FIGS. 1, 7, 8, and 10-12, it will be seen that eitherthe vehicle 10 or the track assembly 14 can have a rotation stopper 130that stops the rotation movement of track assembly 14 around hub 50. Inone embodiment, rotation stopper 130 is mounted on spacers 84 withfasteners 132 and proximate to inside mounting plate 70. Rotationstopper 130 has a slot 134 in the middle therein. Vehicle 10 is providedwith a member 136 (FIGS. 10-12) having a portion slidably inserted inslot 134 and another portion mounted on the vehicle 10. The rotationmovement of track assembly 14 stops when the member 136 abuts one end ofslot 134. Rotation stopper 130 prevents the track assembly 14 to enterin contact with a vehicle wing and spoil the latter.

It will be obvious to people skilled in the art that the presentinvention can be applied both in the case of a two-wheel drive vehiclewherein the power is typically applied only to the rear track beltassemblies and the front track assemblies merely facilitate steering,and in the case of a four-wheel vehicle, wherein power is independentlyprovided to each one of the four track assemblies. It is also understoodthat, although the present invention has been described in the contextof a four-wheeled all-terrain vehicle (ATV), it could also be applied toother vehicles including various straddle-type vehicles, such as dirtbikes, motorcycles and three-wheeled ATV.

As will be further understood by one skilled in the art, the all-terrainvehicle 10, equipped with track assemblies according to the presentinvention, may be viewed as a snow vehicle since it may be used on snowas efficiently as conventional snow vehicles such as snowmobiles, forexample. The wide supporting footprint of the track assemblies is animportant factor allowing this good performance. However, the absence ofsliding shoes allows the use of the all-terrain vehicle on hardersurface without the usual drawbacks of tracked vehicles.

Interestingly, the present track assembly system can equip all fourwheels of an all-terrain vehicle or only the front or rear wheelsthereof. A further possibility would be to use track assembliesaccording to the present invention in place of the rear wheels of avehicle, while mounting skis in place of the front wheels thereof.Another important advantage of the track assembly 14 is that the sametrack assembly 14 can be mounted in any position on the vehicle (front,rear, left and right).

The embodiments of the invention described above are intended to beexemplary only. The scope of the invention is therefore intended to belimited solely by the scope of the appended claims.

1. A track assembly for an all-terrain vehicle comprising: alongitudinal endless track belt having an outer surface and an innersurface; and a mounting structure to mount said longitudinal endlesstrack belt to said vehicle, said mounting structure including at leastone driving wheel disposed externally to said longitudinal endless trackbelt, said at least one driving wheel being in driving engagement withsaid longitudinal endless track belt; and at least two inner wheels incontact with said inner surface of said longitudinal endless track belt.2. A track assembly as claimed in claim 1, wherein said longitudinalendless track belt is in meshing engagement with teeth provided on saidat least one driving wheel.
 3. A track assembly as claimed in claim 2,wherein said meshing engagement is provided by said teeth engaging withtransversal lugs provided on said outer surface of said endless trackbelt.
 4. A track assembly as claimed in claim 1, wherein said at leasttwo inner wheels are idler wheels.
 5. A track assembly as claimed inclaim 1, further comprising a tension adjusting assembly for adjustingthe tension of said endless track belt.
 6. A track assembly as claimedin claim 1, further comprising a vertical position adjusting means forsaid inner wheels such that a shape of said longitudinal endless trackbelt may be modified.
 7. A track assembly as claimed in claim 1, whereinsaid at least one driving wheel is adapted to be drivingly connected tothe driving output of the straddle type vehicle for transmitting powerto said endless track belt.
 8. A straddle-type vehicle including atleast one track assembly to support said vehicle onto a ground surface,said at least one track assembly comprising: a longitudinal endlesstrack belt having an outer surface and an inner surface; a frame tomount said longitudinal endless track belt to said vehicle; at least onedriving wheel disposed externally to said longitudinal endless trackbelt, said at least one driving wheel being in driving engagement withsaid longitudinal endless track belt; and at least two inner wheels incontact with said inner surface of said longitudinal endless track belt.9. A straddle-type vehicle as claimed in claim 8, wherein thestraddle-type vehicle is selected from a group consisting of: a dirtbike and a all-terrain vehicle.
 10. A straddle-type vehicle as claimedin claim 8, wherein said endless track belt is in meshing engagementwith teeth provided on said at least one driving wheel.
 11. Astraddle-type vehicle as claimed in claim 10, wherein said meshingengagement is provided by said teeth engaging with transversal lugsprovided on said outer surface of said endless track belt.
 12. Astraddle-type vehicle as claimed in claim 8, wherein said inner wheelsare idler wheels.
 13. A straddle-type vehicle as claimed in claim 8,wherein said driving wheel is mounted to a hub of said all-terrainvehicle.
 14. A straddle-type vehicle as claimed in claim 8, wherein saidat least one track assembly is part of a pair of front track assembliesand wherein said vehicle further comprises: at least one independentbraking system operatively connected to said at least one driving wheel;the braking systems of said track assemblies being selectivelyindependently actuable, whereby upon actuating one of said brakingsystem, said driving wheel operatively associated with said actuatedbraking system slows down allowing said vehicle to turn in the directionof said slowed down driving wheel.
 15. A mechanism for facilitating thesteering of an all-terrain vehicle having a pair of track assemblies,each track assembly having at least one driving wheel, the mechanismcomprising at least one first and second braking systems operativelyconnected to respective driving wheels of said pair of track assemblies;said first and second braking systems being independently actuable,whereby upon activating one of said first and second braking systems,the driving wheel operatively associated with said actuated brakingsystem is slowed down to facilitate turning of the vehicle in thedirection of the slowed down driving wheel.
 16. A mechanism as claimedin claim 15, wherein said first and second braking systems form part ofa secondary braking system of the vehicle.
 17. A mechanism as claimed inclaim 15, wherein each of said first and second braking systemscomprises: a braking member positioned proximate to said driving wheel;and an actuator to activate said braking member; and whereby, uponactivating said actuator, said braking member abuts said driving wheeland slow down the rotation movement of said driving wheel.